Tuesday, September 26, 2006

Genetic Controls

A post by Cornelius Hunter entitled 'Cellular Software' can be found at ID the Future. The italicized article follows.

At first the information revolution in molecular biology consisted mainly of static data. Increasing numbers of protein and DNA sequences were scanned, followed by whole genomes. Then came the ability to detect genetic activity. The cellular response could be analyzed by observing which genes are active and which are dormant in response, for instance, to a particular environment. These data are now revealing a fascinating network of coordinated cellular responses, as exemplified in recent findings of how cells repair damaged DNA. [1]

DNA damage is not uncommon and so the cell's DNA repair capability is important. A variety of repair mechanisms and machinery have been elucidated in recent decades, but research published earlier this year illustrates how these different mechanisms work together, in a coordinated fashion. In the experiments, researchers used methyl-methanesulfonate to damage DNA in yeast cells, causing minor structural aberrations.

In the painstaking experiments, the exposed cells rapidly identified the damage, ceased several normal functions as if going into a lock-down mode, removed the damaged DNA, and coordinated a battery of mechanisms to insert a fresh copy of the DNA segment. As one researcher put it, "it’s almost as if cells have something akin to a computer program that becomes activated by DNA damage, and that program enables the cells to respond very quickly." Indeed, what was discovered is an elaborate system of genetic control that is triggered by DNA damage.

A result of the research is that various pathways that had been known to be associated with DNA damage are now explained in a single circuit diagram. As is often the case, however, these valuable results are really just the tip of the iceberg. There are many more questions to be answered about the cell's operations manual. As one researcher reflected, "the point of this is to generate novel ideas that then lead to more hypothesis-driven experiments."

This is empirical science. The goal is to figure out how nature works (the cell in this case), and this is done by generating hypotheses about the cell's design.

1. C.T. Workman, et. al., "A Systems Approach to Mapping DNA Damage Response Pathways," Science, 312:1054-1059, 2006.

Could a cell function in the absence of "an elaborate system of genetic control that is triggered by DNA damage?" How would such as system evolve when genomic safeguards do not exist? If the genome of a putative precursor cell could not function without the genetic controls then how does a stochastic/selection process generate life?



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